Less than two weeks after a Caltrans technician was fired for allegedly falsifying data, the agency's director sent a letter urging prosecutors to reconsider their decision not to file criminal charges against the former employee.

"In light of information that has recently been brought to my attention, I am asking you to reconsider filing criminal charges against former Caltrans employee Duane Wiles," Caltrans Acting Director Malcolm Dougherty wrote to U.S. Atty. Benjamin D. Wagner and the Sacramento County district attorney.

"Mr. Wiles engaged in criminal acts … by fabricating the results of structural engineering tests performed on several highway construction projects," Dougherty wrote.

Wiles and his supervisor, Brian Liebich, were fired Nov. 8 and did not return calls to listed numbers.

Last week, the agency released thousands of pages of documents related to the firings. Officials said they took the action ahead of a state Senate Transportation and Housing Committee meeting last Tuesday.

The documents lay out when and where Wiles was caught falsifying data, and how Caltrans officials responded. The agency stressed that the San Francisco-Oakland Bay Bridge was not involved in any of the falsified data and that the projects on which Wiles had allegedly fabricated information were structurally sound.

The first incident officials said they became aware of, according to the documents, was at the La Sierra Avenue Bridge in Riverside in September 2008. Wiles was assigned to use a device that emits radioactive gamma rays to determine the density of concrete.

He "was immediately caught falsifying data" by an engineer, according to the documents, and another technician was called to retest the data. About four months later, Wiles' supervisor, Liebich, wrote that "no other incidences of impropriety existed other than the singular event."

But the engineer who caught Wiles at the bridge investigated further and found two other projects on which Wiles had allegedly falsified data.

The next incident officials discovered was during a project in April 2007 in which workers widened a bridge with retaining walls in Culver City, part of an effort to add lanes to the 405 Freeway.

The third was in March 2008 when Wiles was assigned to conduct tests on the I-580 overhead sign project in Alameda County.

Caltrans said that in response to the incidents, they created new testing requirements including forms designed to ensure that the entire process is documented.

Dougherty sent a letter to the transportation committee's chairman, State Sen. Mark DeSaulnier (D-Concord), saying "the actions of this employee and his supervisor … were unacceptable and reprehensible."

"Better controls should have been in place at that time to prevent such activities. Documentation should have been more thorough and timely, and remedial action should have been swifter," Dougherty wrote.

But after the Tuesday meeting, DeSaulnier said the hearing raised "many unanswered questions."

"There seems to have been a complete breakdown of review and control within one arm of Caltrans," DeSaulnier said.

"Caltrans also seems to have failed in its duty to report to the Toll Bridge Program Oversight Committee," he said. "These are critical problems, and the Transportation and Housing Committee will aggressively follow up."